Bioworld Underoos Boys Superman Underwear Shirt Set Top: 100% Cotton Importado Officially Licensed Boy's Superman Underwear and Shirt Set Soft Stretch Fabric, Slim Fit, and Colorfast designs Top: 100% Cotton, Bottom: 95% Cotton, 5% Spandex Sizing: X-Small(Chest 22"/ Waist 21 1/2"-22 1/2") Small(Chest 24" / Waist 23" - 24") Medium(Chest 26 1/2" / Waist 24 1/2" - 25 1/2") Large(Chest 28"-29 1/2" / Waist 26"-27")